Transmitter and circuits therefor



N. H. HOLLAND.

TRANSMITTER AND CIRCUITS THEREFOR.

APPLICATION FILE-D SEPT. 26, 1917.

Patented N 0v. 22, 1921" STATE UNt' NEWMAN H. HOLLAND, OF WEST ORANGE, NEW EERSE Y, ASSIGNOR TCLNEW at;

PATENT COMPANY, OF WEST ORANGE, NEW JERSEY, A CORPORATION OF LJQJW JERSEY.

menace.

T all whom it may concern:

Be it known that I, NEWMAN H. HOLLAND,

a subject of the King of Great Britain, and a resident of West Orange, Essex county, New Jersey, have invented certain new and useful Improvements in Transmitters and (lircuits Therefor, of which the following is a description.

My invention relates to telephone transmitters and more particularly to microphone transmitters for use with phonograph recorders each having an electro-magnet and diaphragm controlled thereby and wherein the desired variations of current are produced by variations in electricalresistance 1 caused by varying the pressure upon a quantity of finely divided granular conductive material, such as carbon, which is included between electrodes in the circuit carrying the current, the requisite changes in'pressure be ing effected between the electrodes and the granular material by the action of sound waves from a source of sound, such as the human voice, on a diaphragm or other suitable means.

Heretofore it has been customary to have a 'ather appreciable quantity of granular material in the transmitter, which material was confined between the frontand back electrodes which were separated. This arrangement required caretul ad ustment of v the parts and introduced an undesirable re sistance in the circuit.

, Granular carbon is one of the best conductive materials for use in transmitters;- It has been found that while suchtcarbon has a very high resistance when cold, yet when heated the resistance proportionately de creases, making it more sensitive and responsive to movements of the diaphragm.

in the usual form of transmitters the initial. resistance when the c1rcu1t 1S closed is quite high and falls slowly as the carbon becomes heated during the passage of the current. The sensitiveness of former constructions of transmitters therefore increased very slowly and when such transmitters, have been used in connection with phonograph recorders the records have been unsatisfactory in some re spects.

in particular the invention resides in pro- Specification of Letters Patent.

. Application filed September 26, 1917.

The object of the present invention is to TRANSMITTER AND CIRCUITS THEREFOR.

' Patented N or 22 1921. Serial No. 193,232.

yiding means for instantly and quickly heatmg the conductive material and in prdviding a construction in which less conductive material is necessary so that the material can be very quickly heated with little initial current as soon as the circuit is closed.

The above object may be obtained in various ways, and in the present disclosure I have provided a construction in which the electrodes initially short-circuit the conductive material between them when the circuit is open or at the instant it is closed.

To short-circuit the conductive material the electrodes are electrically connected preferably by having them initially in direct contact with each other. Means is then provided for simultaneously breaking the connection between the electrodes and causmg an induced current through the circuit.- This means comprises a suitable device such as an electro-magnet, to break the direct connection between the electrodes or to separate them a predetermined distance the instant that the circuit is closed. T he separation of the electrodes increases the resistance of or substantially breaks the circuit, the conductive material between the electrodes, which is usually carbon, being of high risistance. The increased resistance in the circuit and separation of the electrodes causes the induced current, preferably a current selfinduced by reason of the presence in the circuit of the coil of the electro-magnet for separating the electrodes or of the electromagnet of the recorder or both. Tlhe indubed current isof greater voltage and passes from one electrode to the other through the conductive material or carbon heating it. The conductive material is agitated and shaken simultaneously with the separation of the electrodes and the passage 'of the induced current. The agitation or shaking of the conductive material increases its sensitiveness, the action being anz'ilogous to coherer action in Hertzian wave apparatus. The, conductive material 'is, therefore, instantly heated and an electrical connection of low resistance between the electrodes is insured,

in the accompanying drawing, which forms a part of this specification, and in which like reference characters refer to like parts in the several views Figure 1 is aview of the preferred em- 'bodiment of my invention with parts in secv tion, together with a diagrammatic. representation of the circuit employ-ed.

Fig. 2 is an end view of the back of the I transmitter.

'. the remainder of the transmitter.

Referring to the drawing the numeral 1 designates a mounting ring of the trans.--

mitter while 2 is a mouth piece provided with an annular flange 3. The flange is inserted into the ring and securedby means of ring 4;. Behind the flange but spaced therefrom by a gasket 6 of rubber or similar mascrew threaded into the bridge piece so that the magnet can be moved or adjusted toward or away from the diaphragm and'ls held in adjusted position by means of'a nut 15. On'the extension below the bridge piece there is threaded a right angled or L shaped.

iron heel piece 16 one leg of which extends parallel to the axis of the magnet. To the lower end of this leg is pivoted as at 17 an arm 18 carrying a second or. back electrode 19 located between the magnet and 'diaphragm. The arm 18 may or may not be,

- though preferably is,'made of magnetic material. The back electrode is rigidly secured to the arm 18 by a pm 20 driven through the arm and into the electrode.

separates the arm and the electrode. "The back electrode hasits front surface roughened so as to increase the area of contact between it and finely divided or granular conductive material or carbon 22 interposed between the electrodes and to allow the electhe carbon.

trodes to engage without interference from The back electrode is surrounded by a ring 23 of-fibrous material such as felt so as to -form a cell to retain the carbon 22. .r a In practice one end of the core 13 is spaced but a short distance from the pin'20 and limits the movement of the back electrode.

The .electro-magnet- 1 2 and core can be so adjusted that the electrodes will separate a predetermined amount only. The adjust- I The pin is preferably of magnetic material and is provided with an enlarged head. Washer 21' ment, for instance, should be so determined thatj buzzing, due to the vibration of the back electrode between the diaphragm and corefis prevented. The diaphragm 7 and back'gelectrode 19 when the circuit is open, are in contact. The back electrode is urged into this positionby a spring 24. The electrode supporting arm' 18, together with the electrode .itself, is adjustable toward and. from the diaphragm by means of the screw threaded connection between the heelpiece 16 and extension 14 and is held in position by means of a nut 25. This last adjustment permits the back electrode 19 to beadjusted relatively to .the diaphragm and relativelyto the core. l

The transmitter is shown in circuit with a source of electrical energy 26 and a recorder'or other electro-magnetic device 27.

The recorder comprises a diaphragm 28 which is controlled by an electro-magnet 29 having a coil 30 in the circuit of the transmitten and the'c'oil 12 and-preferably in series with the transmitter and in parallel with the coil 12 The path of'the current is such that when a contro1ler'31 is closed the. current will flow from the source to the mounting ring 1, diaphragm or front electr0de'7, back electrode 19, pin 20, arm 18,

heel piece 16, screw 16 through magnet coil 12 and back to the source. From the heel piece 16 a parallel path is provided for part of the current via bridge piece 9-to the recorder 27 and then backto the source 26. By placing the recorder in parallel with the electro-magnet coil 12 theresistance througlijthe circuit is materially reduced andthe-jpresence of the coil 12" will not decrease the sensitiveness of the recorder. The magnet 12 after the conductive mate- ,rialis heated only requires enough current to hold :the back electrode out of contact -with th' front one. j

The operation of my improved transmitter is substantially as follows:

When .-th e circuit isopen, or at the instant .it'is closed, the electrodes 7 and19 are-substantially-Yin contact; the resistance in the rial which .-is"normally of high resistance is then short-circuited.

When the circuit is closed, a momentarily large flow of current energizes the magnet 12, drawing the-back electrode quickly rearwardly out of contact with the front elec- --trode or diaphragm. The movement of the niagnet circuit, therefore, will be compara- "tively small 'fbec'ause the conductive mate- "learner creased or the circuit is substantially broken. At this instant a rapid reduction of current takes place through the coil 12 and the coil 30, causing an induced current of substantially high voltage. through the circuit,- through the granular or conductive material and from one electrode to the other, instantly heating the conductive material, reducing its resistance and making it very sensitive. The passage of this induced current of high voltage through the conductive turn converts the electrical impulses into mechanical or sound Waves and aitects the record 32. little current to operate the same.

It is to be understood that my invention is not limited to the embodiments and features specifically shown and described herein, but that such features and embodiments are subject to changes .and modifications Without any departure from the spirit of the invention.

.Having now described my invention, what l claim as new and desire to protect by Letters Patent of the United States, is as follows:

1. In a device of the character described, a circuit, granular conductive material subject to variations in resistance permanently included in said circuit and the sensitiveness of which in respect of such variations is atl ected by its temperature, and means acting momentarily upon the closing of the circuit.

to cause said material to reach its maximum sens1t1veness -1n respect ofsuch variations, substantially as described.

2,111 a device of-the character described,

a circuit, granular conductive material subject to variations in resistance permanently included in said circuit, and means for affecting said circuit to cause a'momentary induced current therethrough of suflicient magnitude to heat said material to the point of maximum. sensitiven'ess in respect of such variations,"v substantially as described.

3. In adevice of the characterdescribed, a circuit, aquantit-y of granular conductive material permanentlyincluded in said circuit, and means for affecting said. circuit otherwisethan by variation in resistance of My construction requires very.

said material for causing a momentary induced current therethrough, substantially as described.

4. In adevice of the character described, a circuit, a quantity of granular conductive material permanently included in said circuit and adapted to be short-circuited, and means for causing an induced current through said material when the short-circuit is broken, substantially as described.

5. In a transmitter, acircuit comprising electrodes having granular conductive material unvarying in amount between them and adapted to be electrically connected, shortcircuiting said material, and means for breaking said shcr -circuiting connection, substantially as described.

6. In a transmitter, a circuit comprising electrodes having granular conductive material unvarying in amount between them and adapted to be electrically connected, shortcircuiting said material, and means for causing an induced current through said material when the short-circuiting connection is broken, substantially as described.

7. In a transmitter, a circuit comprising electrodes having a fixed amoiint of conducy tive material interposed between them, said" electrodes being initially electrically connected, short-circuiting said material, and means for disconnecting said electrodes and causing an induced current through said material whereby it is instantly heated, substantially as described.

8. in a transmitter, the combination of electrodes movable relatively to and initially engaging each other, conductive material unvarying in quantity interposed between said electrodes, and means for separating said electrodes and causingan induced current to' cross between the separated electrodes and through the conductive material, substantially as described. i

9. ln a transmitter, the combination of electrodes movable relative to and initially in contact with each other, one of saidelectrodes having a pocket orcell extending close to the other electrode, conductive material in said pocket or cell, and means for causing conductive material in said cell between said electrodes, means pressing one of said electrodes normally into contact with the other to short-circuit said conductive material, and means for causing the separation of said electrodes when the circuit is closed and an induced current through the materialfsubstantially as described.

11. In a transmitter, a circuit comprising an electrode arranged to vibrate in acordance with pulsations transmitted thereto, a second actuating the same whereby the electrode, and conductive material interposed. between said electrodes, means for electrically connecting said electrodes short circuiting the conductive material, an electro-magnet interposed in said circuit and controlling said means whereby said electrodes are disconnected andwhereby an induced current will be discharged between said electrodes and through said conductive material, substantially as described.

12. In a transmitter, the combination of electrodes movable relative to each other, a quantity of conductive material permanently disposed between said electrodes, means to cause said electrodes to short-circuit said conductive material and electro-magnetic means for moving said electrodes relatively to each other, substantially as described.

13. In a transmitter, the combination of electrodes movable relative to each other, one of said electrodes having a pocket or cell extending close to the other electrode, conductive materialin said pocket or cell, means to hold said .electrodes in contact with each other so as to short-circuit said conductive material and electro-magnetic means for moving said electrodes relative to each other, substantially as described.

14. In a transmitter, the combination of electrodes movable relatively to each other, one of said electrodes having its inner surface roughened, conductive material interposed between said electrodes, means causing said electrodes to directly engage each other, short-circuiting said' conductive material and means for causing the separation of said electrodes when the circuit is closed and an induced current to pass through the conductive material, substantially as described.

15 In a transmitter, the combination of an electrode arranged to vibrate in accordance with pulsations transmitted thereto, a second electrode movable relatively to the first and initially in direct contact with the first, conductive material interposed between said electrodes, an electromagnet in series with saidelectrodes and having a core extending toward said movableelectrode-for magnet causes the separation of the electrodes and the core'acts as a stop, thereby jarring the conductive material and a current of high voltage passes between said electrodes and through said conductive material instantly heating the same, substantially as described, 7

16. Ina transmitter, the combination with an electrode arranged to vibrate in accordance with pulsations transmitted thereto, a second electrode movable relatively to the first, conductive material interposed between "said electrodes, means for holding said sec}.

0nd electrode in contact with the first elec electrotrode, thereby short-circuiting the conductive mater al, electro-magnetlc means comprising a coil for moving said second electrode out of engagement with the first electrode,sa1d coil being in series with said electrodes and conductive material whereby,

the armature and initially in contact with the diaphragm and conductive material interposed between 'the electrodes, substantially as described.

18. In a transmitter, a frame, a diaphragm mounted upon said frame and constituting an electrode, an electro-magnet having a core securing "the same to the frame, a heel piece attached to the core, an armature pivoted to said heel piece and extending between the electro-magnet and the diaphragm, a secondelectrode attached to said armature and controlled by said electro-magnet, conductive material interposed between said electrodes, means for causing said electrodes to engage,' said electrodes,

heel piece, conductive material and electromagnet being 1n series whereby when the circuit is closed the electrodes separate and" a current of relatively high voltage crosses between the electrodes and through the conductive material heating the same, substan' tially as described.

19; The combination of a transmitter comprising electrodes and conductive material interposed between the-electrodes, said.

electrodes being initially electrically connected to short-circuit said material, means for disconnecting said electrodes and an electro-magnetic device interposed in circuit with said transmitter, substantially a described.

20. The combination of a transmitter comprising electrodes movable relatively to each other and initially in contact, conductive material interposed between said electrodes and initially short-circuited, means comprising an electro-magnet in the circuit of said transmltter for causlng the separa tion ofi aid electrodes, andan electro-magnetic. device having a coil in circuit with said transmitter, substantially as described.

21. The combination with 'a transmitter comprising electrodes and conductive material interposed' between the electrodes, of means comprising an electro-magnet for controlling the electrodes and an electrorear magnetic device in parallel With said elec tromagnet, substantially as described.

22. The combination with a transmitter comprising relatively movable electrodes initially in contact and conductive material interposed between the electrodes and initially short-circuited, of an'clectro-magnet having a coil in series with said electrodes, for moving said electrodes relatively to each other, separating them, and inducing a current to heat the conductive material, and an electromagnetic device in parallel with the coil of said elect-ro-magnet, and in series with said electrodes, substantially asidescribed. v 1 23. The, combination with a transmitter comprising a pair of electrodes with conductive material interposed between them, and an electro-magnet comprising a coil for controlling said electrodes, of a phonograph recorder having an electromagnetic coil in series with said electrodes and, in parallel with said coil, ubstantially as described.

24. In a device of the character described,

electrodes movable relatively to and biased conductive material interposed between said electrodes, and means for separating said electrodes and causing an induced current to cross between the separated electrodes and through the conductive material, substantially as described.

25. lln a device of the character described, a circuit comprising relatively. movable electrodes and a quantity of conductive material permanently disposed between the electrodes, said electrodes initially occupying a position closely adjacent each other, means operable upon the closing of the circuit for suddenly separating said electrodes and for causing a momentary induced current to cros between the separated electrodes and through the conductive material, and means operable upon the breaking of the circuit for'restoring said electrodes to their initial position, substantially as described. This specification signed and witnessed this 19th day of September, 1917.

NEWMAN H. HOLLAND.

Witnesses:

Clans. H. Keenan, JAooB Unfi 

